The football club Borac Banja Luka was founded on 4 July 1926. Originally it was named Radnički sportski klub Borac, which means Labour Sports Club Borac, and its roots come from the relation the club had with labour movements during the first half of the 20th century. The club was founded by a group of football aficionados including the writer, activist and People's Hero of YugoslaviaVeselin Masleša, Rudolf "Rudi" Hiter, Savo Novaković, Nikola Pucar, Brane Pucar, Mustafa Softić, Nikola Kuković, Žarko Vranješević, Mile Stefanović, Brane Stefanović and others. They were mostly commercial assistants who believed that they could contribute a more efficient fight for workers rights by establishing the football club. The name "Borac" (English: fighter) was given by Masleša who said: "If you are going to fight for workers rights, why don't you give the club name Borac".[1][2]

The club's first president was Rudolf Hiter, and Savo Novaković was named vice president, with supervisory board headed by Đoko Jovanović. Before World War II started, training and everything else related to football, official and unofficial, was located in the surrounding of Banja Luka. As football attracted more and more attention in the city on the Vrbas river, there was a need for new, bigger and modern stadium. The opening ceremony of the newly built stadium took place on September 5, 1937, on the ground of the present-day Banja Luka City Stadium. The club's first success in this early period came in 1928, when RSK Borac won a tournament played in Sarajevo. Before World War II, the major club in Banja Luka was SK Krajišnik, however, after 1945 Borac replaced Krajišnik as city´s main club. Borac played conference leagues in order to qualify for the reestablished Yugoslav First League where defeated Sloboda Novi Grad 14–3 on aggregate, FK Kozara from Banja Luka with 8–4 on aggregate and Borac Kozarska Dubica 7–0 on aggregate and became Banja Luka district champions. In 1945, RSK Borac was renamed in FK Borac Banja Luka and played for two years in the Yugoslav Third League, before it was promoted to the Yugoslav Second League in 1953.

In 1961, Borac was promoted to the Yugoslav First League for the first time, but was promptly dropped back down at the end of the season. The club had to wait for almost a decade for the return to top flight. It was in the 1970/71 season, and the club stayed in the top league for four consecutive seasons. In this period, precisely in 1974, Borac achieved the Yugoslav Cup final. They were defeated by Hajduk Split in Belgrade, and as the runner-up, they have provided placement for the 1975–76 European Cup Winners' Cup season. In the first round of Cup Winners' Cup, Borac played against US Rumelange from Luxembourg. The first leg was played in Banja Luka where Borac recorded a record win in European competitions by a 9–0.[3]

The second leg was won by Borac by 1–5, meaning 14–1 on aggregate, and played in the second round against R.S.C. Anderlecht. The "Red-Blues" won the home match but it was 1–3 on aggregate at the end for the Belgians, who became winers of the European Cup Winners' Cup that season. Borac Banja Luka was the only team who beat R.S.C Anderlecht in one match (at home by 1–0) during the cup season. In the 1974–75 season, Borac played in the second league, but the club achieved a quick promotion and thus ensured the beginning of a new 5-year first league period that lasted until 1980. The following nine seasons, Borac spent in the second League, before a final top league period between 1989 and 1992. Borac's best placement in the first League was in 1992, when it finished the season as 4th. In total, Borac played 487 matches in Yugoslav First League during a 46 years long period.[4]

From 1988–92, Borac enjoyed the best period in its long history. In 1988, Borac achieved its biggest success. Under coach Husnija Fazlić team won the Yugoslav Cup, the second major football competition in the former Yugoslav football and became the only second league club that ever achieved this. In the final, Borac defeated Yugoslav football giant Red Star by 0–1 at JNA stadium in Belgrade.[5][6][7][8] The historic goal was scored by Senad Lupić, one of the Borac's legends. At the ceremony, president of Yugoslav Football Association Antun Čilić gave the golden plaques to Borac players and head coach. The next day, tens of thousands of Borac supporters gathered at Krajina square in Banja Luka and gave their team a hero’s welcome.

At that time there was a war in home Bosnia, full scale Serbian military aggression in neighbour Croatia and growing Bosnian Serb aggression in Bosnia, but despite that, they travelled to Italy in hope to write history. After the elimination of U.S. Foggia in front of 30,000 spectators, Borac met in the final BVSC Budapest at Pino Zaccheria Stadium. Filipović scored but gave only temporary advantage to Borac because the Hungarians equalized by Tuboly. That was the result of regular time, so the winner was decided by penalties. Borac won 5–3 from the white spot and got the trophy. Sašivarević, Stavljanin, Filipović, Bilbija, and Simeunović scored for Borac, and goalkeeper Simeunović saved his goal twice. Borac head coach was Smilevski, who was recently named as the member of Borac's "Best Eleven" squad in its history. Borac played a total of twelve games in UEFA competitions and has never lost a European match at its home ground. Also, seven Borac players have participated in the Yugoslav national football team in its history.

It became the country's most prestigious level of football competition. Also, since 2002, the clubs from entire country are competing in the Bosnia and Herzegovina Football Cup. In 2010, Borac won the Bosnia and Herzegovina Cup and finished as third the national championship. During the 2010–11 UEFA Europa League season, they played in the second round against FC Lausanne-Sport, but were knocked out in front of sold-out Banja Luka City Stadium with 1–2 on aggregate for the Swiss club. In 2011, Borac became the football champion of Bosnia and Herzegovina with only 4 defeats and 15 conceded goals during 30 matches. The club won also the Republika Srpska Cup. In the following 2011–12 UEFA Champions League season, Borac start the qualifying matches against Maccabi Haifa. First match was played in Haifa, where Borac got the lead by the goal from Raspudić, a goal that surprised Maccabi Haifa as they were controlling the game. A minute into the first half's extra time, Amasha equalized for Maccabi Haifa. But then, an inexplicable black hole [clarification needed] occurred at Borac performance and they conceded three goals in only three minutes and Borac lost by 5–1. In the second leg, Borac showed great performance and won 3–2 by two goals from Krunić and one from Vidaković, however, the tournament was over for them. In 2012, Borac finished the national championship as third and qualified for the European football competition season. The draw for the 2012–13 UEFA Europa League was held in Nion and Borac got Čelik Nikšić from Montenegro as their opponent. Borac was knocked out by away goal rule (3-3a).

Borac Banja Luka's traditional home colors are red and blue with white socks (colours that are contained on the Serbian flag). Borac has maintained the red-blue shirt for its home kit throughout the history of the club. Its traditional away colours are all blue or all red. The club's kit is currently manufactured by NAAI, a Serbian sports clothing company.

Borac Banja Luka's present crest contains name of the club and the name of the City of Banja Luka on the background formed from the sections that are colored as Serbian flag. On the top of the crest the year of club foundation is located. In addition, the whole crest is framed with gold color.

The home field of Borac is the Banja Luka City Stadium. It has 9,730 seats and is one of the most modern stadiums in the country. The stadium was built in 1937 by Bogoljub Kujundžić as a donator. Since then, the stadium underwent several expansions and reconstructions in the years 1973, 1981, 2010 and 2012. In 2010, the stadium underwent complete reconstruction. New seats were installed on east and west stands, locker rooms were renovated, a completely new VIP lounge and room for media was built, new lighting, sound systems and video surveillance were installed, and trophy and technical rooms were renovated. In 2012, new north stand was built with a capacity of 2,492 seats, which increased the total capacity of the stadium to 9,730. According to recent plans, the east stand will be covered by a roof in the upcoming years. In the near future, the construction of the south stand will began, which would increase the total capacity to approximately 13,000 seats.

In 2008, expert committee has chosen the concept of building a new stadium. The new stadium will have 30,000 seats, and whole complex will cover 205,000 square meters. It will include two additional football fields, tennis, basketball and volleyball courts. The cost of the whole project is estimated to be €50 million and it will meet the highest FIFA an UEFA demands.[citation needed]

As one of the most successful football club in country, Borac always had considerable number of supporters. The organized supporters of FK Borac are known as Lešinari[13] (Serbian Cyrillic: Лешинари) and they are the oldest organized supporter group in Republika Srpska, Bosnia and Herzegovina. They were established in 1987. The gathering point of the club's most loyal and passionate fans is the East stand of Banja Luka City Stadium.